defmodule RecycledCloud.OpenNebula.VMPool do
  @moduledoc """
  OpenNebula VM Pool: http://docs.opennebula.io/5.12/integration/system_interfaces/api.html#one-vmpool-info
  """
  alias RecycledCloud.OpenNebula, as: ONE
  alias RecycledCloud.OpenNebula.Schema

  # Filters ressourses.
  # (user) ID >= 0 matches an user's resources.
  @filter_flags [
    {:user_primary_group, -4},
    {:user, -3},
    {:all, -2},
    {:user_and_groups, -1}
  ]

  def get(%{filter_flag: filter_flag} = params) when is_atom(filter_flag) do
    params
    |> Map.put(:filter_flag, Keyword.get(@filter_flags, filter_flag))
    |> get()
  end

  def get(%{range_start: :infinite} = params) do
    params |> Map.put(:range_start, -1) |> get()
  end

  def get(%{range_end: :infinite} = params) do
    params |> Map.put(:range_end, -1) |> get()
  end

  def get(%{state_filter: state} = params) when is_atom(state) do
    params |> Map.put(:state_filter, ONE.VM.state_for(state)) |> get()
  end

  def get(%{
    filter_flag: filter_flag,
    range_start: range_start,
    range_end: range_end,
    state_filter: state,
    kv_filter: kv_filter
  }) do

    fn location ->
      params = [filter_flag, range_start, range_end, state, kv_filter]
      case ONE.query(location, "one.vmpool.info", params) do
        {:ok, raw} ->
          data = raw
                 |> Schema.scan("vm_pool")
                 |> Schema.map_record
          {:ok, data}
        {:error, err} -> {:error, err}
      end
    end
  end
end